WHO/CDC announced their recommended vaccines for the 2018-19 flu season. Once again, the vaccines computed by FutureFlu were a perfect match with that of WHO/CDC. The BLASTP comparison of H3N2 strains A/Slovenia/342/2017 (recommended by FutureFlu) and A/Singapore/INFIMH-16-0019/2016 (recommended by WHO/CDC) shows 100% identities with 0% gaps.
According to The Francis Crick Institute report, “H3N2 viruses have become increasingly difficult to characterize antigenically by HI assay”. HI (hemagglutinin inhibition) assay relies on the agglutination (i.e. clumping) of red blood cells (RBCs) by the influenza virus. It is used for calculating the efficacy of an influenza vaccine against a virus strain.
The report states that the HA assay is losing viability because H3N2 viruses are no longer agglutinating the RBCs effectively. Also, the results are becoming less repeatable.
Above findings support the need for supplementing the HI assay used by WHO with alternate methods such as the reverse vaccinology model developed by FutureFlu.
FutureFlu recommends an A/Slovenia/342/2017-like (SL17) strain for the H3N2 component of the 2018-19 flu vaccine. Further, A/Michigan/45/2015 (MI15), the current H1N1pdm vaccine should be continued. The composition of the H3N2 vaccine was calculated with the Fourier-enhanced Phylogeny/Antigenicity Predictive Model (F^P/A-PM) developed by FutureFlu. The model suggests that the new vaccine should incorporate the N120K, R141G, N170K, I405V, G478E and G483E mutations over the current vaccine.
According to the WHO Weekly Report dated 04 Sep 2017, Type A influenza (H1N1pdm and H3N2) continues to dominate the flu sickness. 89.2% of the reported cases are affected by it. FutureFlu is extending the Prediction Model to H3N2, with an emphasis on epitopes A-E on the HA segment of H3.
FutureFlu had recommended A/Michigan/45/2015 as the H1N1pdm component of the flu vaccine in January 2017. It belongs to the Clade 6B.1. How does it compare to the emerging Clade 6B.2? The analysis using the Antigenic Prediction Model shows that the drift between the two Clades is still within the limits of vaccine efficacy.
The World Health Organization has announced the vaccine for the 2017-18 flu season. The A/Michigan/45/2015 strain recommended by WHO is a perfect match with A/Montana/04/2016 recommended by FutureFlu.
Strains from Clade 6B.1 continue to dominate H1N1pdm (www.cdc.gov/flu/weekly/pdf/External_F1708.pdf). A/Montana/04/2016 is much more closely associated with Clade 6B.1 genetically than the current vaccine strain A/California/07/2009 .
In their Weekly U.S. Influenza Surveillance Report dated February 10, 2017, CDC stated “The HA gene segment of all influenza A (H1N1)pdm09 viruses analyzed belonged to genetic group 6B.1” (www.cdc.gov/flu/weekly/pdf/External_F1705.pdf).
The A/Montana/04/2016 vaccine recommended by FutureFlu belongs to the same Clade 6B.1. It further supports the analysis by FutureFlu and the need for a new vaccine.
Based on the phylogenetic and antigenicity analyses, FutureFlu recommends an A/Montana/04/2016-like vaccine for the 2017-18 flu season, preferably using a recombinant specimen.
FutureFlu has developed a novel Antigenicity Prediction Model of the hemagglutinin inhibition (HI) assay. It estimates the avidity of the antibodies generated by a vaccine towards an influenza strain. It uses the proteomic sequences of the strains and the antisera.